The eyesight protective glasses against the harmful effects of sunbeams are known. In its simplest form, a glass is made of a glass lamella usually bent in two perpendicular directions and of a substantially constant thickness in the case of a non corrective glass. The material used for producing the lamella may be mass tinted or an absorbing and/or reflecting layer can be arranged superficially in order to obtain a filtering effect for the light rays. Various improvements are also known. It is thus possible to arrange a layer of an anti-reflecting material at the surface of the lamella. Similarly, it is also possible to combine a polarizing film to the glass so as to attenuate polarized light rays in a determined direction and more particularly as a result of a reflection from a surface, usually the ground, covered with snow or water. However, as the polarizing film is made in a plastic material and is relatively breakable, it is glued in sandwich between two glass lamellae.
The resulting structures are therefore made of materials having different filtering and appearance spectral features and the global effect on all the light rays is not always optimal. In particular, it seems difficult to obtain a structure that would be both appropriate to filter the day-time sun light beams which have a broad spectrum and the night-time artificial light sources which vary considerably. The light sources that can be encountered at night are, in the eye sensitivity area, generally monochromatic or comprise few emission lines. This is specially the case for electrical gas discharge light sources that are used for public lighting. Moreover, the automotive lighting, beside broader spectrum incandescence sources, also begins to use discharge lamps that seem to be more aggressive visually. In all cases, the artificial light sources that are most frequently encountered at night have a spectrum that is relatively remote from the sun spectrum.